1. Field of the Invention
The present invention relates to an electronic timepiece which performs the demonstration of the pointer movement in which a pointer is moved on a test basis.
2. Background Art
For example, there has been known an electronic timepiece in which a user can move a pointer of a timepiece is by rotating a crown in a state where the crown is pulled up thus adjusting time or correcting the positional displacement of the pointer (see JP-A-5-196754 (patent document 1), for example).
This electronic timepiece performs the demonstration of the pointer movement in which when a user pushes the crown in a pulled-up state, when the crown is returned to a normal state where the electronic timepiece exhibits the timing function from a correction state for correcting the pointer, the pointer is rotated by a fixed amount and, thereafter, the pointer is reversely rotated to an original position.
However, in the demonstration of the pointer movement, when the pointer is not rotated in accordance with a control part which controls a rotational amount of the pointer, there may be a case where the pointer does not return to an original position after the demonstration of the pointer movement. When the pointer does not return to the original position in this manner, it is necessary for the user to push a manipulation button so as to return the pointer whose position is displaced to the original position. Here, with respect to the manipulation button, to consider a case where there is only the manipulation button which performs the forward movement of the pointer in the clockwise direction and there is no manipulation button which performs the backward movement of the pointer in the counterclockwise direction, when the pointer is displaced in the clockwise direction only by 1 scale in the demonstration of the pointer movement, there arises a drawback that a pointer returning operation using only the forward pointer movement imposes a large burden on a manipulation by the user.
Hereinafter, the explanation is made in detail by taking, for example, as shown in FIG. 15A and FIG. 15B, an electronic timepiece where as a rotary shaft of a motor which gives power to a pointer, a rotary shaft M having a circular columnar shape which has one half columnar portion thereof formed of an N pole and another half columnar portion thereof formed of an S pole is subject to electromagnetic induction so that the pointer movement is generated as an example.
In the demonstration of the pointer movement, when the forward pointer movement is performed by 30-scale pointer movement (1-scale pointer movement meaning the rotation of the rotary shaft which moves the pointer by 1 scale, the same definition being applicable hereinafter), when a stop state of the rotary shaft M (that is, a motor drive polarity indicative of the relationship between the polarity of the rotary shaft M and the polarity generated by electromagnetic induction) is not recognized in advance, with the first 1-scale pointer movement in the backward pointer movement, the motor drive polarity is brought into an attractive state. Accordingly, the pointer is rotated in the counterclockwise direction by 29 scales due to the backward pointer movement and is rotated in the clockwise direction by 30 scales due to the forward pointer movement thus giving rise to a drawback that the pointer does not return to the original position.
To be more specific, as shown in FIG. 15A and FIG. 15B, a coil C is wound around a rotary shaft supporting member K which rotatably supports the rotary shaft M, and a magnetic field is generated in the rotary shaft supporting member K when an electric current is supplied to the coil C. Since the polarity of the magnetic field generated in the rotary shaft supporting member K and the polarity of the rotary shaft M repel each other, the rotary shaft M is rotated and power is imparted to a pointer.
When an electric current I which flows in the direction P is supplied to the coil C in a state where an S-pole magnet of the rotary shaft M is on an L side of the rotary shaft M and an N-pole magnet of the rotary shaft M is on an R side of the rotary shaft M as shown in FIG. 15A, the motor drive polarity becomes the repulsive polarity so that the rotary shaft M is rotated.
On the other hand, when an electric current I which flows in the direction P is supplied to the coil C in a state where the N-pole magnet of the rotary shaft M is on the L side of the rotary shaft M and the S-pole magnet of the rotary shaft M is on the R side of the rotary shaft M as shown in FIG. 15B, the motor drive polarity becomes the attractive polarity so that the rotary shaft M is not rotated. In this case, by supplying an electric current I which flows in the direction Q to the coil C, the motor drive polarity becomes the repellant polarity so that the rotary shaft M is rotated.
For example, when the demonstration of the pointer movement is performed after a battery is exchanged, a control part which supplies the electric current I to the coil C does not recognize a state of polarities of the magnets which constitute the rotary shaft M. Accordingly, the motor drive polarity becomes the attractive polarity so that the rotary shaft M of the motor is not rotated in the first pointer movement, is rotated in the counterclockwise direction by an amount of 29 scales due to the backward pointer movement, and is rotated in the clockwise direction by an amount of 30 scales due to the forward pointer movement. Accordingly, in the demonstration of the pointer movement, the pointer is displaced in the clockwise direction by 1 scale.
Accordingly, in returning a second hand whose 1 cycle is constituted of 60 scales to an original position, it is necessary to return the second hand to the original position by pushing a button 59 times.
Further, in the case where a minute hand is connected to the second hand by means of a gear train, one rotation of the second hand in the clockwise direction makes the minute hand advance by 1 scale. Accordingly, to adjust the positional displacement of both of the second hand and the minute hand, it is necessary to push the button 3599 times.
Accordingly, there arises a drawback that an extremely large burden is imposed on a user who performs a manipulation to correct the positional displacement of a pointer caused by the demonstration of the pointer movement.